Best Flash for D610

Just picked up a D610. Couldn't find the answer in a search, so could anyone tell me what are the fully compatible Nikon Flash units for this camera?

I have an SB 800 for my D90 and a backup SB 600. I see presently it looks like the SB 910 and SB 700 are current flashes. Would the SB 700 be a step up from from the 800 I presently have, or would it pay to spring for the SB 910? I'm mostly thinking of power output as when I shoot a wedding and such, I use a Fong diffuser or bouce, so power is the criteria. THough I do use the commander remote control sometimes. that is not the main crtieria.